1. Field of the Invention
The invention relates to an apparatus for reducing torsional vibration by reciprocal motion or pendulum motion of an inertial mass body.
2. Description of Related Art
Examples of an apparatus of this kind are described in Japanese Patent Application Publication No. 8-93855 (JP 8-93855 A) and Japanese Patent Application Publication No. 8-93854 (JP 8-93854 A). In each of these apparatuses, an inertial mass body is structured as a rolling body. The rolling body is formed such that an axial length thereof is longer than a plate thickness of a rotating body, and an annular groove, a width of which is slightly larger than the plate thickness of the rotating body, is formed for an entire circumference of the rolling body in a central section in an axial direction thereof. In particular, in the apparatus described in JP 8-93854 A, the rolling body is configured by including two members: a roller that is formed with a flange-shaped projection at one end, and a side plate that is formed separately from the roller and attached to another end of the roller. Each of the rolling bodies described in JP 8-93855 A and JP 8-93854 A has a so-called H-shaped section. The rolling body is housed in a guide hole that is formed in the rotating body. A portion of an inner surface of the guide hole that is on an outer side in a radial direction of the rotating body serves as a guide surface, and a bottom section of the above annular groove contacts the guide surface. A portion of the rotating body is held in the annular groove, that is, between the projection and the side plate, just as described. In this way, displacement of the rolling body in the axial direction is restricted. In addition, Japanese Patent Application Publication No. 2013-185598 (JP 2013-185598 A) describes a rolling body in which a surface corresponding to an inner side surface of the above annular groove is formed as a tapered surface.